Bioreactor Expansion Affects Microbial Succession of Mixotrophic Acidophiles and Bioremediation of Cadmium-Contaminated Soils.

Microbial scale-up cultivation is the first step to bioremediating cadmium (Cd)-contaminated soils at the industrial scale. However, the changes in the microbial community as the bioreactor volume expands and their associations with soil Cd removal remain unclear. Herein, a six-stage scale-up cultivation process of mixotrophic acidophiles was conducted, scaling from 0.1 L to 10 m3, to remediate Cd-contaminated soils. The findings showed that bioreactor expansion led to a delay in sulfur and glucose oxidations, resulting in a reduced decline in solution pH and cell density. There were minimal differences observed in bacterial alpha-diversity and community structure as the bioreactor volume increased, except for the 10 m3 scale. However, bioreactor expansion decreased fungal alpha-diversity, changed the community structure, and simplified fungal community compositions. At the family level, Acidithiobacillaceae and Debaryomycetaceae dominated the bacterial and fungal communities throughout the scale-up process, respectively. Correlation analysis indicated that the indirect effect of mixotrophic acidophiles played a significant role in soil Cd removal. Bacterial community shifts, driven by changes in bioreactor volume, decreased the pH value through sulfur oxidation, thereby indirectly enhancing Cd removal efficiency. This study will contribute to the potential industrial application of mixotrophic acidophiles in bioremediating Cd-contaminated soils.

Regulation of hydrogen binding energy via oxygen vacancy enables an efficient trifunctional Rh-Rh2O3 electrocatalyst for fuel cells and water splitting.

Developing multi-functional electrocatalysts is of great practical significance for fuel cells and water splitting. Herein, Rh-Rh2O3 nanoclusters are prepared and the surface oxygen vacancy content is regulated elaborately by post-treatment. The optimized Rh-Rh2O3/C-400 exhibits superior trifunctional catalytic activity for hydrogen oxidation reaction (HOR), hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), i.e., the mass activity for HOR is 2.29 mA µgRh-1, and the overpotential for HER and HzOR at 10 mA cm-2 is as low as 12 mV and 31 mV, respectively, superior to the benchmark Pt/C. Rh-Rh2O3/C-400 also displays promising performance in practical devices, with the H2-O2 anion-exchange-membrane fuel cell delivering a peak power density of 0.66 W cm-2, and the hydrazine-assisted water splitting electrolyzer requiring a low electrolysis voltage of 0.161 V at 0.1 A cm-2. The experimental and theoretical investigations discover that the hydrogen binding energy (HBE) is linearly depended on surface oxygen vacancy contents, and the HBE directly determines the catalytic activity for HOR, HER and HzOR. This work not only innovates an efficient Rh-based nanocluster tri-functional electrocatalyst, but also eludicates the intrinsic relationship of surface structure-intermediate adsorption-catalytic activity.

The Cd immobilization mechanisms in paddy soil through ureolysis-based microbial induced carbonate precipitation: Emphasis on the coexisting cations and metatranscriptome analysis.

Microbial induced carbonate precipitation (MICP) can immobilize metals and reduce their bioavailability. However, little is known about the immobilization mechanism of Cd in the presence of soil cations and the triggered gene expression and metabolic pathways in paddy soil. Thus, microcosmic experiments were conducted to study the fractionation transformation of Cd and metatranscriptome analysis. Results showed that bioavailable Cd decreased from 0.62 to 0.29 mg/kg after 330 d due to the MICP immobilization. This was ascribed to the increase in carbonate bound, Fe-Mn oxides bound, and residual Cd. The underlying immobilization mechanisms could be attributed to the formation of insoluble Cd-containing precipitates, the complexation and lattice substitution with carbonate and Fe, Mn and Al (hydr)oxides, and the adsorption on functional group on extracellular polymers of cell. During the MICP immobilization process, up-regulated differential expression urease genes were significantly enriched in the paddy soil, corresponding to the arginine biosynthesis, purine metabolism and atrazine degradation. The metabolic pathway of bacterial chemotaxis, flagellum assembly, and peptidoglycan biosynthesis and the expression of cadA gene related to Cd excretion enhanced Cd resistance of soil microbiome. Therefore, this study provided new insights into the immobilization mechanisms of Cd in paddy soils through ureolysis-based MICP process.

A clinical study on roxadustat for anemia in diabetic nephropathy: a 8-week study.

PURPOSE: The development of roxadustat is a standard treatment for renal anemia, and multiple clinical trials have proved its safety and efficacy. However, less information is available from trials of the population with diabetic nephropathy (DN). This study aimed to determine whether roxadustat is effective for treating DN. METHODS: This was a single-center, retrospective, institutional review board-approved cohort study. The patients with DN were chosen and given roxadustat or erythropoietin (EPO) for 8 weeks. The mean hemoglobin (Hb) level after 8 weeks of treatment served as the primary outcome. Alterations in the iron index and lipid levels were considered secondary objectives. Sub-group analysis was performed to observe the impact of inflammation and glycemic status on Hb. RESULTS: A total of 80 patients were enrolled, 40 in each group. After 8 weeks of treatment, the Hb levels in the roxadustat group were higher than those in the control group. The number of patients who achieved Hb response was higher in the roxadustat group than in the control group (77.5% versus 27.5%; P < 0.001). In addition to lowering total cholesterol and low-density lipoprotein cholesterol, roxadustat decreased ferritin and elevated total iron-binding capacity. Compared to the control group, roxadustat was more beneficial for patients with an inflammatory condition and poor glycemic control. CONCLUSIONS: Roxadustat treatment remarkably corrected anemia in patients with DN, and its effectiveness was unaffected by inflammation or glycemic control levels. In addition, roxadustat can also reduce a patient's blood lipid level and enhance the body's use of iron. CLINICAL TRIAL REGISTRATION: ChiCTR2200057232.

Transport Behavior of Cd2+ in Highly Weathered Acidic Soils and Shaping in Soil Microbial Community Structure.

The mining and smelting site soils in South China present excessive Cd pollution. However, the transport behavior of Cd in the highly weathered acidic soil layer at the lead-zinc smelting site remains unclear. Here, under different conditions of simulated infiltration, the migration behavior of Cd2+ in acid smelting site soils at different depths was examined. The remodeling effect of Cd2+ migration behavior on microbial community structure and the dominant microorganisms in lead-zinc sites soils was analyzed using high-throughput sequencing of 16S rRNA gene amplicons. The results revealed a specific flow rate in the range of 0.3-0.5 mL/min that the convection and dispersion have no obvious effect on Cd2+ migration. The variation of packing porosity could only influence the migration behavior by changing the average pore velocity, but cannot change the adsorption efficiency of soil particles. The Cd has stronger migration capacity under the reactivation of acidic seepage fluid. However, in the alkaline solution, the physical properties of soil, especially pores, intercept the Cd compounds, further affecting their migration capacity. The acid-site soil with high content of SOM, amorphous Fe oxides, crystalline Fe/Mn/Al oxides, goethite, and hematite has stronger ability to adsorb and retain Cd2+. However, higher content of kaolinite in acidic soil will increase the potential migration of Cd2+. Besides, the migration behavior of Cd2+ results in simplified soil microbial communities. Under Cd stress, Cd-tolerant genera (Bacteroides, Sphingomonas, Bradyrhizobium, and Corynebacterium) and bacteria with both acid-Cd tolerance (WCHB 1-84) were distinguished. The Ralstonia showed a high enrichment degree in alkaline Cd2+ infiltration solution (pH 10.0). Compared to the influence of Cd2+ stress, soil pH had a stronger ability to shape the microbial community in the soil during the process of Cd2+ migration.

Study on the Biomolecular Competitive Mechanism of Polybrominated Diphenyl Ethers and Their Derivatives on Thyroid Hormones.

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants. PBDEs and their derivatives, hydroxylated PBDEs (OH-PBDEs), can bind to hormone receptors and impact hormone secretion, transportation, and metabolism, leading to endocrine disruption and the development of various diseases. They have particularly strong interference effects on thyroid hormones. This study used decabromodiphenyl ether (BDE-209); 2,2',4,4'-tetrabromodiphenyl ether (BDE-47); and 6-OH-BDE-47 as representative compounds of PBDEs and their derivatives, OH-PBDEs. A fluorescence probe, fluorescein-isothiocyanate-L-thyroxine (FITC-T4, F-T4), specific for binding to transthyretin (TTR), a thyroid transport protein, was prepared. The binding capacity of PBDEs and their derivatives, OH-PBDEs, to TTR was quantitatively measured using fluorescence spectroscopy. The principle of quenching the fluorescence intensity of F-T4 after binding to TTR was used to analyze the competitive interaction between the probe and BDE-209, BDE-47, and 6-OH-BDE-47, thereby evaluating the toxic effects of PBDEs and their derivatives on the thyroid system. Additionally, AutoDock molecular docking software (1.5.6) was used to further analyze the interference mechanism of OH-PBDEs on T4. The results of the study are as follows: (1) Different types of PBDEs and OH-PBDEs exhibit varying degrees of interference with T4. Both the degree of bromination and hydroxylation affect their ability to competitively bind to TTR. Higher bromination and hydroxylation degrees result in stronger competitive substitution. (2) The competitive substitution ability of the same disruptor varies at different concentrations. Higher concentrations lead to stronger substitution ability, but there is a threshold beyond which the substitution ability no longer increases. (3) When OH-PBDEs have four or more bromine atoms and exhibit the most structural similarity to T4, their binding affinity to TTR is stronger than that of T4.

Leaching Behavior of As and Pb in Lead-Zinc Mining Waste Rock under Mine Drainage and Rainwater.

At present, the pollution of arsenic (As) and lead (Pb) is becoming increasingly serious. The pollution caused by the release of As and Pb from lead-zinc mines has seriously affected the water and soil environment and threatened human health. It is necessary to reveal the release characteristics of As and Pb. The actual scene of mine drainage (MD) and rainwater (RW) leaching waste rocks is the one of the main reasons for the release of As and Pb. However, the leaching behavior of As and Pb in these waste rocks under MD and RW suffered from a lack of in-depth research. In this study, we investigated the occurrence of As and Pb in waste rocks (S1-S6) by using X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (TOF-SIMS), and then, the changes in As and Pb concentration and the hydrochemical parameter in leaching solution were systematically studied. Furthermore, the correlation between the release of As and Pb and mineral composition was also evaluated. Results showed that these waste rocks were mainly composed of carbonate and sulfide minerals. As and Pb were mainly bounded or associated with sulfide minerals such as arsenopyrite, pyrite, chalcopyrite, and galena in these waste rocks, and small parts of As and Pb were absorbed or encased by clay minerals such as kaolinite and chlorite. Under MD and RW leaching, the pH, redox potential (Eh), and electric conductivity (EC) of each waste rock tended to be consistent due to their buffering ability; the leachate pH of waste rocks with more carbonate minerals was higher than that of sulfide minerals. Both As and Pb were released most under MD leaching in comparison to RW, reaching 6.57 and 60.32 mg/kg, respectively, due to MD's low pH and high Eh value. However, As in waste rock released more under alkaline conditions because part of the arsenic was in the form of arsenate. As and Pb release were mainly positively correlated with the proportions of sulfide minerals in these waste rocks. MD leaching significantly promoted the release of As and Pb from waste rocks, which would cause a great threat to the surrounding environment, and control measures were imperative. This paper not only reveals the As and Pb pollution mechanism around the lead-zinc mining area but also provides a theoretical basis for the prevention and control of As and Pb pollution in the future.

Effect of roxadustat on iron metabolism in patients with peritoneal dialysis: a real-world 24-week study.

BACKGROUND: Roxadustat is an oral hypoxia inducing factor-prolyl hydroxylase inhibitor (HIF-PHI) that regulates iron metabolism in patients with chronic kidney disease (CKD) primarily by reducing hepcidin levels and mobilizing internal iron stores. More data are needed to demonstrate the efficacy of roxadustat in regulating iron metabolism in patients with peritoneal dialysis (PD) compared with erythropoiesis stimulating agents (ESAs). METHODS: This prospective cohort study enrolled PD patients with a mean hemoglobin level of 60-100 g/L. All subjects were randomized into two groups at a ratio of 2:1 the roxadustat group (106 cases), and the ESA group (53 cases). The primary endpoint was the change in the iron biomarker levels and the proportion of patients with absolute iron deficiency and functional iron deficiency. RESULTS: Compared with ESAs, roxadustat significantly decreased hepcidin level (difference, - 20.09 ng/mL; 95% CI, - 30.26 to - 9.92), attenuated the increase in serum soluble transferrin receptor (sTFR) level (difference, - 7.87 nmol/L; 95% CI, - 12.11 to - 3.64), and reduced the proportion of patients with functional iron deficiency (roxadustat, 11.43%; ESA, 33.33%). There was no significant difference in safety of the two groups over the duration of the study. CONCLUSIONS: Compared with ESA group, roxadustat group showed significant differences in all iron biomarker levels except serum ferritin (sFt) and transferrin saturation (TSAT). These results suggest that roxadustat was superior to ESAs as a therapy for iron metabolism in PD patients. TRIAL REGISTRATION: This study completed Chinese Clinical Trial Registration on March 4, 2022 (registration number: ChiCTR2200057231).

Tuning C1 /C2 Selectivity of CO2 Electrochemical Reduction over in-Situ Evolved CuO/SnO2 Heterostructure.

Heterostructured oxides with versatile active sites, as a class of efficient catalysts for CO2 electrochemical reduction (CO2 ER), are prone to undergo structure reconstruction under working conditions, thus bringing challenges to understanding the reaction mechanism and rationally designing catalysts. Herein, we for the first time elucidate the structural reconstruction of CuO/SnO2 under electrochemical potentials and reveal the intrinsic relationship between CO2 ER product selectivity and the in situ evolved heterostructures. At -0.85 VRHE , the CuO/SnO2 evolves to Cu2 O/SnO2 with high selectivity to HCOOH (Faradaic efficiency of 54.81 %). Mostly interestingly, it is reconstructed to Cu/SnO2-x at -1.05 VRHE with significantly improved Faradaic efficiency to ethanol of 39.8 %. In situ Raman spectra and density functional theory (DFT) calculations reveal that the synergetic absorption of *COOH and *CHOCO intermediates at the interface of Cu/SnO2-x favors the formation of *CO and decreases the energy barrier of C-C coupling, leading to high selectivity to ethanol.

Co-occurrence network in core microorganisms driving the transformation of phosphorous fractionations during phosphorus recovery product used as soil fertilizer.

Phosphorus recovery from water and the subsequent reuse of its products can solve both water eutrophication and phosphorus resource waste issues. However, the potential use of the final recovered products as crop phosphorus fertilizers and the transformation of phosphorus fractions in soils have rarely been analyzed. In this study, the effects of a phosphorus recovery product (w-HC/CSH/P) obtained from our previous phosphorus recovery study on pepper growth were investigated. The association between soil phosphorus fraction transformation and the microbial co-occurrence network was investigated using high-throughput sequencing. The results showed that amendment with w-HC/CSH/P could promote the growth and chlorophyll content of pepper, which exhibited high phosphorus fertilizer efficiency. In addition, applying w-HC/CSH/P in soils could increase the microbial alpha-diversity during pepper cultivation and induce changes in the microbial community, leading to an increase in the relative abundance of Povalibacter, Lysobacter, and GP10 and a decrease in GP17. The proportion of Resin-P and NaHCO3-Po decreased, whereas that of NaOH-Po increased during pepper cultivation. psOTU331 (g_Latescibacteria), psOTU377 (g_Lysobacter), and psOTU461 (g_Pseudoxanthomonas) were the key microorganisms driving the transformation of phosphorus fractionation in the microbial co-occurrence network. Latescibacteria and Lysobacter were closely correlated with the transformation of NaHCO3-Po to NaOH-Po, and Pseudoxanthomonas was significantly correlated with a decrease in Resin-P. These observations highlight the potential of phosphorus recovery products as fertilizer for pepper and provide new insights into the transformation of phosphorus fractions corresponding to the microbiome in soils.

Purification and water resource circulation utilization of Cd-containing wastewater during microbial remediation of Cd-polluted soil.

The purification and water resource circulation utilization of cadmium-containing leachate is a key link in the field application of microbial remediation in Cd-polluted soil. In this study, through a simulation experiment of microbial remediation of Cd-polluted paddy soil, the feasibility of the purification and recycling process of wastewater derived from microbial remediation of Cd-polluted soil was explored. The results of the microbial mobilization and removal experiment showed that the concentrations of Cd, N, P, and K in the leachate were 88.51 µg/L, 38.06, 0.53, and 98.87 mg/L, respectively. The leachate also contained a large number of microbial resources, indicating that it had high recovery values. To recycle this wastewater, activated carbon (C), humic acid (H), and self-assembled monolayers on mesoporous supports (SAMMS; S) were used as adsorbents. The results showed that the co-existing cations in the leachate had a major influence on the adsorption of Cd. In the ternary system of Fe, Al, and Cd, the removal efficiency of Cd increased to 91.2% when the S dosage was increased to 5‰, and the sorption of Cd occurred after Fe and Al. However, C and H exhibited poor adsorption performances. The isotherm models further showed that the maximum adsorption capacities of S, H, and C were 13.96, 6.41 and 2.94 mg/g, respectively. The adsorption kinetics of S showed that adsorption was a rapid process, and the C-H and O-Si-O of S were the key functional groups. The pH of the leachate significantly affected the adsorption efficiency of Cd. Finally, the purified leachate was successfully applied to microbial cultivation and soil remediation. Overall, the reclamation of Cd-containing wastewater can not only dampen the impacts of water shortages, but also achieve the purposes of Cd removal and resource recovery to lower costs by approximately 1166-3499 yuan per mu.

A review on the bioleaching of toxic metal(loid)s from contaminated soil: Insight into the mechanism of action and the role of influencing factors.

The anthropogenic activities in agriculture, industrialization, mining, and metallurgy combined with the natural weathering of rocks, have led to severe contamination of soils by toxic metal(loid)s. In an attempt to remediate these polluted sites, a plethora of conventional approaches such as Solidification/Stabilization (S/S), soil washing, electrokinetic remediation, and chemical oxidation/reduction have been used for the immobilization and removal of toxic metal(loid)s in the soil. However, these conventional methods are associated with certain limitations. These limitations include high operational costs, high energy demands, post-waste disposal difficulties, and secondary pollution. Bioleaching has proven to be a promising alternative to these conventional approaches in removing toxic metal(loid)s from contaminated soil as it is cost-effective, environmentally friendly, and esthetically pleasing. The bioleaching process is influenced by factors including pH, temperature, oxygen, and carbon dioxide supply, as well as nutrients in the medium. It is crucial to monitor these parameters before and throughout the reaction since a change in any, for instance, pH during the reaction, can alter the microbial activity and, therefore, the rate of metal leaching. However, research on these influencing factors and recent innovations has brought significant progress in bioleaching over the years. This critical review, therefore, presents the current approaches to bioleaching and the mechanisms involved in removing toxic metal(loid)s from contaminated soil. We further examined and discussed the fundamental principles of various influencing factors that necessitate optimization in the bioleaching process. Additionally, the future perspectives on adding omics for bioleaching as an emerging technology are discussed.

Heteroatom-Doped Asymmetric Metal-Nx -C Single Atom Catalysts for Electrochemical CO2 Reduction Reaction.

CO2 utilization is one of the hottest research topics worldwide. As a class of newly emerging and promising catalysts for electrochemical CO2 reduction (ECR) reaction, heteroatom-doped metal-Nx -C single atom catalysts (M-Nx -C SACs) attract extensive attentions. Nowadays, great progress, including structure modulation, identification of local coordination environment and ECR mechanism via advanced synthetic strategies, characterization techniques and theoretical calculations, have been achieved over heteroatom doped asymmetric M-Nx -C SACs, which boost the ECR performances and deepen the understanding of ECR mechanism. In this context, we summarize recent progresses in heteroatom-doped asymmetric M-Nx -C SACs, with emphasis on synthetic strategies and their applications in ECR reaction, along with current understanding on the ECR mechanisms both experimentally and theoretically. Finally, the challenges and perspectives for the heteroatom-doped asymmetric M-Nx -C SACs towards ECR are proposed.

Insight into functional microorganisms in wet-dry conversion to alleviate the toxicity of chromium fractions in red soil.

Soil contamination with potentially toxic element such as chromium (Cr) poses a threat to the environment and human health. The environmental toxicity of Cr is related not only to the total Cr content but also to the distribution of Cr fractions. In this study, laboratory simulation experiments were conducted to explore the characteristics of Cr fractions and responses of the functional microbial community during dynamic leaching and static drying processes. The results showed that acid-soluble Cr and reducible Cr transformed into other relatively stable fractions under dry conditions, and ammonium nitrogen promoted the transformation. Nitrate-nitrogen was significantly positively correlated with Cr fractions in the wet stage (p < 0.05), while ammonium nitrogen showed the same relation in the dry process. Analysis of the microbial community showed that the bacterial and fungal genera Flavihumibacter, Altererythrobacter, Methylobacillus, Flavisolibacter, Lysobacter, and Cladosporium were related to the Cr fractions (acid-soluble Cr, reducible Cr, and oxidizable Cr) under wet conditions, while the microbial genera Ellin6067, MND1, and Ramlibacter were related to Cr fractions under dry conditions. Moreover, the proliferation of the functional microbial genera Methylobacillus, Ellin6067, and MND1 related to Cr fractions in the wet-dry conversion process alleviated the environmental toxicity of Cr. These findings provide useful information for the remediation of Cr-contaminated soils by monitoring the distribution fractions of Cr and the functional microbial community under wet-dry conditions.

Effect of Sacubitril/Valsartan on renal function in patients with chronic kidney disease and heart failure with preserved ejection fraction: A real-world 12-week study.

Patients with chronic kidney disease (CKD) are often complicated with heart failure with preserved ejection fraction (HFpEF). However, several drugs, including angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB), have not shown apparent benefits in terms of morbidity and mortality of HFpEF. PARAMOUNT and other studies have shown the potential benefits of Sacubitril/Valsartan on patients with HFpEF, but its effects on renal function and the effect of low-dose Sacubitril/Valsartan in actual clinical conditions have not been thoroughly evaluated. In our longitudinal and observational research, 353 patients were followed up for 12 weeks. We evaluated renal function [urinary protein, serum creatinine and estimated glomerular filtration rate (eGFR)] and cardiac function [NT-proBNP (brain natriuretic peptide), New York Heart Association (NYHA) classification, left ventricular ejection fraction (LVEF), left atrial width and left ventricular end-diastolic width] at baseline and during follow-up. Worsening renal function (WRF) was defined as an increased serum creatinine≥26.5umol/L or decreased eGFR≥20%. The decline of eGFR in the Sacubitril/Valsartan group was slower than that in the control group (p = 0.021). The outcome of proteinuria in the ACEI/ARB group was significantly better than that in the Sacubitril/Valsartan group (p = 0.001). In terms of echocardiogram, the average left atrial width in Sacubitril/Valsartan group decreased by 1.38 ± 3.02 mm, which was significantly lower than that in the ACEI/ARB group (p = 0.02). The increase of urine protein class in the ACEI/ARB group increased the risk of WRF with statistical significance (OR = 2.36, 95%CI 1.01-5.49, p = 0.047), but no statistical significance was found in all the patients or Sacubitril/Valsartan group. In conclusion, Sacubitril/Valsartan could more effectively slow down renal function decline and reverse myocardial remodeling in patients with CKD and HFpEF than ACEI/ARB, even at low doses, though its protective effect on urinary protein is not as good as that of ACEI/ARB.

An interconnected-graphene enveloped titanium dioxide flower as a robust support for proton exchange membrane fuel cells.

Support corrosion is a traditional intractable problem for oxygen electrodes of fuel cells, so developing anti-corrosion supports is highly desirable. Herein, we fabricate a three-dimensional (3D) interconnected-graphene enveloped titanium dioxide flower (TiO2@RGO) as a robust support for the oxygen reduction reaction (ORR). Benefiting from the unique 3D architecture, the TiO2@RGO composite possesses both a large surface area of 174 m2 g-1 and a superior electrical conductivity of 0.19 S cm-1, enabling an electron highway for efficient simultaneous mass transfer of reactants. After loading Pt nanoparticles, the Pt-TiO2@RGO catalyst exhibits a similar catalytic activity to the commercial Pt/C catalyst, while superior stability under the accelerated degradation protocols for both catalysts (0.6-1.0VRHE) and supports (1.0-1.5VRHE), due to the strong metal-support interaction (SMSI) of Pt nanoparticles and the TiO2@RGO composite support. The PEMFC with the Pt-TiO2@RGO cathode delivers a peak power density of 901 mW cm-2, which is comparable to that with a Pt/C cathode. This work proposes a new strategy for designing robust catalyst supports for PEMFCs.

Cadmium, lead and arsenic contamination in an abandoned nonferrous metal smelting site in southern China: Chemical speciation and mobility.

The investigation of chemical speciation of primary toxic metal(loid)s (Cd, Pb, and As) in soil profile in nonferrous metal smelting site is a key to the assessment of their mobility characteristics and formulation of subsequent remediation strategy. In this study, 74 soil samples were collected at 12 different soil profiles; soil physio-chemical properties and total content of Cd, Pb and As and corresponding chemical speciation were also determined. The results showed that the mean total concentration followed the order of Pb > As > Cd. A large proportion of Pb, Cd and As were accumulated in upper soil profiles (depth < 3 m). Heavy pollution of Pb, Cd and As were observed in the whole soil profile at the area of fuel oil storage tank (ZY6) and lead smelting area (ZY8). The dominant fraction of Cd was exchangeable fraction (F1); Pb was dominant in Fe/Mn oxides-bound fraction (F3) in most cases; Crystallized Fe/Al hydrous oxides bound fraction (F4) generally accounted for a large proportion of As. Mobility factor (MF) followed the order Cd > As > Pb, indicating that Cd was the most mobile element in soil profiles. Pearson correlation analysis found that MFCd was significantly positively correlated to soil silt; the F4 fraction percentage of As was significantly positively correlated to soil redox potential (Eh). Additionally, MFCd/Pb was found to be positively correlated to crystalline iron (Fec), while negatively correlated to amorphous iron (Feo). The findings reported in this study, on the basis of distribution characteristics of chemical speciation could provide a new solution for future soil remediation at the site. Long-term solutions to metal(loid)s pollution might be offered by microbial-assisted soil washing technique that promotes the transformation of Fe/Mn oxides-bound fraction and organic/sulfide-bound fraction.

Anderson-Type Polyoxometalate-Assisted Synthesis of Defect-Rich Doped 1T/2H-MoSe2 Nanosheets for Efficient Seawater Splitting and Mg/Seawater Batteries.

Designing high-performance hydrogen evolution reaction (HER) catalysts is crucial for seawater splitting. Herein, we demonstrate a facile Anderson-type polyoxometalate-assisted synthesis route to prepare defect-rich doped 1T/2H-MoSe2 nanosheets. As demonstrated, the optimized defect-rich doped 1T/2H-MoSe2 nanosheets display low overpotentials of 116 and 274 mV to gain 10 mA cm-2 in acidic and simulated seawater for the HER, respectively. A magnesium (Mg)/seawater battery was fabricated with the defect-rich doped 1T/2H-MoSe2 nanosheet cathode, displaying the highest power density of up to 7.69 mW cm-2 and stable galvanostatic discharging over 24 h. The theoretical and experimental investigations show that the superior HER and battery performances of the heteroatom-doped MoSe2 nanosheets are attributed to both the improved intrinsic catalytic activity (effective activation of water and favorable subsequent hydrogen desorption) and the abundant active sites, benefiting from the favorable catalytic factors of the doped heteroatom, 1T phase, and defects. Our work presents an intriguing structural modulation strategy to design high-performance catalysts toward both HER and Mg/seawater batteries.

Ecological responses of bacterial assembly and functions to steep Cd gradient in a typical Cd-contaminated farmland ecosystem.

The response of soil bacterial communities from farmland ecosystems to cadmium (Cd) pollution, in which a steep concentration gradient of more than 100 mg/kg has naturally formed, has not previously been fully reported. In this study, a field investigation was conducted in a typical severe Cd-polluted farmland ecosystem, and the bacterial community response to the steep Cd gradient was analyzed. The results showed that Cd concentration sharply decreased from 159.2 mg/kg to 4.18 mg/kg among four sampling sites alongside an irrigation canal over a distance of 150 m. Bacterial diversity and richness were significantly lower in highly polluted sites, and random forest analysis indicated that Cd gradient played a decisive role in reducing alpha diversity. Redundancy analysis (RDA) and co-occurrence network indicated that the synergistic effects of pH, Cd, and phosphorus were the main drivers shaping community structure. The functional results predicted by BugBase suggested that the bacterial community may adapt to the harsh environment by recruiting Cd-resistant microbes and improving oxidative stress tolerance of the whole community. Cd-resistant microorganisms such as Burkholderia, Bradyrhizobium, and Sulfurifustis, which directly or indirectly participate in diminishing oxidative damage of Cd, may play essential roles in maintaining community stability and might be potential bacterial resources for the bioremediation of Cd pollution.

Vertical distribution of the toxic metal(loid)s chemical fraction and microbial community in waste heap at a nonferrous metal mining site.

Over the past few decades, nonferrous mining has produced numerous waste rock and part of the waste that has not been properly treated was generally dumped at roadsides and hill slopes. However, the vertical distributions of toxic metal(loid)s and composition of microbial communities in waste heap and the under-laid pristine soil are rarely studied. In this work, the fraction-related distributions of toxic metal(loid)s were investigated at a waste heap profile and the indigenous microbial assemblages were also analyzed by Illumina sequencing of 16 s rRNA genes. Results showed that compared to the under-laid pristine soil, content of toxic metal(loid)s, especially Cd, As and Pb, in waste rock layer were higher. Most of As in subsoil existed as non-specifically sorbed and specifically-sorbed fractions, which could be ascribed to the migration from the upper layer. The mobility was significantly correlated with Eh, EC, clay content, CEC and the total content of metal(loid)s. Phyla Proteobacteria, Acidobacteria and Firmicutes dominated the microbial communities. The microbial community compositions at the genus level were similar, but their relative abundances were mainly influenced by pH, CEC, Eh, SOM, and bioavailability content of toxic metal(loid)s. Besides, microbial functions of elements (S, Fe, Mn and As) oxidation/reduction and metabolites (siderophore, biosurfactant, organic acid, phosphatase and urease) potentially were used for pollutants bioremediation.